The formula needs to be reworked in general, it was designed before the taming patch went in. It's still a decent baseline guide for pets, but there are more specific things to look for now. For example, if the pet you are taming can spawn at multiple control slots, you will want a generally lower rated pet so it will be the lower control slots. The other thing to watch for is pets with overcapped resists (CU, Cold Drake, Etc.). A CU with 85 cold will rate higher than a CU with 70 cold, however the CU with 70 cold is much better overall, because you can spread the other 4 resists out easier.